Under the new requirements, kindergarten pupils must get an additional dose of the chickenpox vaccine, which means kindergarten students will have a total of two chickenpox vaccines upon starting kindergarten. Students entering the seventh grade must show proof of two additional immunizations: one dose of Tdap (vaccine for tetanus, diphtheria and pertussis) and one dose of a meningitis vaccine.

"These conditions are highly contagious and spread very easily in school-age children," said Dr. Cheryl DePinto, medical director for the Office of School Health at the Maryland Department of Health and Mental Hygiene. "There's an increased risk of spread in schools because kids are in close contact with each other, and immunizations are an important strategy in limiting the spread, both in schools and in the community."

DePinto said that the new requirement for the pertussis vaccine arose partly because in recent years, an increasing number of cases of pertussis have been seen in patients ages 11 to 19. She added that immunizing teenagers would help reduce the incidence of pertussis in younger children, too.

"Many infants get pertussis, and they are at high risk for complications," DePinto said. "We can reduce their exposure by vaccinating older siblings and others in the household."

The booster dose of pertussis is recommended at the age of 11 to 12, which generally corresponds to seventh grade, DePinto said.

School officials strongly encourage students to be immunized before the first day of school. If they're not, they must show proof that they have a doctor's appointment for the necessary shots within 20 days of the first day of class to remain in school.

Proof of the new vaccinations should be submitted to the school nurse before school starts, said Deborah Somerville, coordinator of health services for Baltimore County schools.

"Providing proof of the new vaccines to the school nurse prior to the first day of school will alleviate a lot of confusion and possible miscommunications about who still needs the vaccines," Somerville said.

Speaking to concerns raised by anti-vaccine activists, DePinto said that vaccines have been proved to be safe for children.

"Misinformation about vaccine safety can scare and confuse parents trying to do what is best for their children," DePinto said. "Many decades of research support the safety of vaccines."

Some children may experience minor side effects, according to DePinto, including redness, swelling and discomfort at the injection site. Severe allergic reactions can occur rarely, she added.

DePinto said that research did not support the notion of a link between vaccinations and autism.

"There have been several studies to examine this possible link and no association has been found," DePinto said. "The most recent study by the Centers for Disease Control and Prevention, from 2013, reaffirms previous findings of no causal link between vaccines and autism."

Penny Bramlett, program supervisor for maternal child health programs at the Carroll County Health Department, said that all public and private school students are required to follow the state's immunizations schedule.

"There is a great misconception that private school children are exempt from state laws, but in fact they have to follow the same laws as public school students," Bramlett said.

Maryland does allow for limited exemptions from the required vaccines for medical and religious reasons.

Vaccination requirements are based on recommendations from the Advisory Committee on Immunization Practices and the U.S. Centers for Disease Control and Prevention.

In Maryland, vaccine requirements for schoolchildren are established through a regulatory process that, according to DePinto, include a review of national recommendations by the Department of Health and Mental Hygiene and input from the public.

Vaccine clinics

Health departments throughout the state will host free clinics this month offering vaccines for the new requirements for children going into kindergarten and seventh grade. The state Health Department can help families get other required vaccines for children and adults on a sliding scale fee.

Vaccines can be administered by a family's primary care doctor. Immunizations are also offered by appointment at local health departments. A parent must be present for a child to get the vaccine.